The general objective of this study was to develop a highly efficient, economical andintegrated technology for the removal of nitrogen compounds through denitrification via nitrite. Toachieve this, a modified UASB reactor was designed, set-up and operated using Chilean zeolite asmicrobial support. The results were compared to a conventional UASB reactor used as control. Thevolume of each reactor was 2 L. The reactors operated with synthetic wastewater under the sameoperating conditions (with superficial velocities, vs, of up to 1 m/h) in the first part of the experiment.Later, during the second part of the experiment, only the modified UASB was used, with vs of up to5.5 m/h. In the first part of the experiment, a higher velocity of denitrification in the reactor withzeolite was obtained. Nitrogen removal at the end of this experimental set for both reactors, with a vslower than 1 m/h, was 87%. In the second stage, the modified UASB reactor operated at vs ofbetween 1.5 and 5.5 m/h. Here, it was observed that the removal of nitrite increased significantly.Specifically, at vs values of 2.5, 4.0 and 5.5 m/h, a value of the nitrogen loading rate (NLR) of 1.22 kgN-NO2 -/m3/d was kept constant, achieving nitrogen removal efficiencies of 50%, 65% and 95.5%respectively. This last value proves how highly effective the modified UASB reactor is when operating with vs as high as 5.5 m/h.